What would need to happen for the population of the United States in 2017 to eventually devolve back to dressing, talking, and overall perfectly mimicking the people and culture of 1950s United States. This includes new technologies fashioned in the style of 1950s items such as smartphones looking like vintage telephones and flat-screens that are beveled in wood and use knobs to control etc.
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Typically this doesn't happen. Cultures move forward, not backwards. At any stage, the culture is typically an energetic minimum for the times. Its what we do when we're not expending energy pretending to be a different culture. To have the same set of traits be minimums for two times 65 years apart would be pretty extraordinary.
What could happen to cause this is a powerful dictator. If you had a powerful dictator who was not concerned with the cost of his or her ideas, they could oppose all non-1950s style so violently that the lowest-energy-cost approach would indeed be to revert back to the '50s.
I'd say the hardest part of the story would have to be communication. Much of culture is centered around how people communicate. Modern technology like social media would simply not fit at all with the culture of a previous era. You may have nice bezeled wood screens to look like the '50s, but the culture of the '50s was not designed around anyone being able to pick up the keyboard and Tweet around the world.
A serious, concentrated effort by everyone to do so. Everyone, or nearly everyone, would have to actively want less fuel efficient cars, no Internet, poodle skirts, Jim Crow laws, really nasty chemicals freely in use in the environment, even worse inequality of women, gays and lesbians blackmailed and beaten regularly, and generally give up all of the massive improvements of the USA has gained in the last 60+ years. There are many who work to do exactly that today, who want to make America great again, but, luckily, they don't seem to be the majority.
Without everyone working for it, trying to get things back to the 1950s is going to be really very hard, regardless of the kind of apocalypse you have. Now, if you kill off enough people, you might reduce America down to a small enough population that they all do want to do this. In that sense, pretty much any apocalypse will do, provided it is sufficiently targeted (deliberately or on accident) to leave a select subset of the populace still alive -- generally the mid-to-upper class white males who would have it best in that time frame.